Auto drains remove condensed liquid – usually a mixture of water and compressor lubricant — from compressed air systems. Automatic drains are commonly installed on air receiver tanks, bulk moisture separators, coalescing filters, air dryers, compressor air piping, …

Auto drain (Internal Float Drains)
Internal float drains insert into the bowl of a coalescing filter or moisture separator. Within the device is a float that normally seats on a small orifice. When liquid enters the drain the float rises off its seat, exposing the orifice and allowing liquid to discharge through the stem. As the liquid level drops, the float re-seats and seals the orifice. No compressed air vents in the process.

Auto drain (Timed Solenoid Drains)
These devices consist of two main parts: a timer and a solenoid valve. The timer controls the interval and duration of the solenoid valve’s actuation. Usually the open time can be adjusted from one to sixty seconds, and the closed time can be adjusted from one minute to sixty minutes.

Auto drain (Electronic Level Sensing Drains)
A level sensing drain uses a water capacitance sensor to signal a valve when to open and shut. This approach eliminates the biggest drawback to solenoid timers drains, the loss of compressed air. Level sensing drains are called “demand drains” because they only activate when liquid is present.